IX costs vary by region but in NYC you can expect around $700/m for a 10g port as a startup. Transit costs over an IX port are much higher than crossconnecting directly to a provider, but IX ports are convenient and save a lot of bandwidth cost if you’re good at building relationships.

The network engineering world is very different from software. Relationships are everything and the pricing very opaque. Often pricing and lists of “who is in the building” are even behind NDA. If you are an “eyeball network” (more downloads than uploads) your transit costs will be much cheaper if you know how to negotiate, for example.